One of Britain's most experienced business people has given a full-throated defence of the conglomerate business model.

Sir George Buckley, who is chairman of the UK manufacturer Smiths Group, said there were times when being a conglomerate - a company whose subsidiaries operate in entirely different industries - made good sense.

Smiths has instead insisted that it plans to "actively manage" its portfolio and sell those business whose performance it believes it cannot improve within three years.

Sir George told Sky News: "The logical conclusion of dividing companies up into these pure-plays is that there's only ever one person, one company, that's the natural owner of every…[vertically integrated business] in the world - and that's a nonsensical conclusion to reach.

"I think that conglomerates bring not just diversity, they bring interests, they bring the power of a single balance sheet that you can focus on any one of these end markets and also, depending on the markets they serve, you see diversity.

"Pure-plays are wonderful in expanding markets and they're terrible in contracting markets. So I'm a conglomerate lover."

Asked if he was making a "case for the defence of the status quo" at Smiths, Sir George replied: "Let's hope so."

Conglomerates dominated the ranks of big British business from the 1960s until the mid-1990s.

One of the earliest was Trafalgar House, which began life as a property company but quickly diversified into hotels, shipping, construction and engineering.

Another was BTR, the old British Tyre & Rubber Company, which gradually diversified from those activities to take in packaging, building materials and aircraft components among others.

Tomkins, which earned the nickname "the guns to buns group" because of its ownership of gun-maker Smith & Wesson and the bakery group Ranks Hovis McDougall, was another.

All of these businesses were assembled on the premise that, if a company's management was good at running one particular activity, there was no reason why it would not be good at running another.

Uniting all these businesses was the fear they struck into the hearts of rivals. All were aggressively run and thrived on buying what they perceived to be under-valued or badly-run businesses and shaking them up. Critics said their success was based largely on financial engineering and on "asset stripping".

Probably the most famous - and feared - of them all was Hanson Group.

Built from a greetings card business, it diversified into agricultural supplies, batteries, bricks, shops, paper, tobacco, coal and energy to become one of the UK's biggest companies.

Its high water mark probably came when, in 1991, it sought to buy chemicals and pharmaceuticals giant ICI, then a bellwether for British manufacturing and industry, only to be beaten when ICI mounted an aggressive defence, revealing many details about the way in which Hanson was run, including its ownership of racehorses.

Although it would be another five years before the company was broken up by its founder, the late Lord Hanson, .the damage was done. One by one, amid growing evidence that investors had fallen out of love with the business model, all of the other conglomerates broke themselves up.

This is why Sir George's comments are so fascinating.

Moreover, the model is arguably having a renaissance at Melrose, the industrial business run by a group of former Hanson managers.

The perspective of Sir George, one of the few Britons to have run a Fortune 500 company, is important because for more than a decade he was been at the helm of two of America's biggest conglomerates - Brunswick Corporation from 2000 to 2005 and then 3M, the company famous for Scotch tape and Post-It notes, from 2005 to 2012.

Apart from Smiths, he is also chairman of Stanley Black & Decker, one of the world's biggest makers of industrial tools and household hardware, while he also sits on the boards of Hitachi, the Japanese industrial conglomerate and PepsiCo, the US food and drink giant.

He was speaking to Sky News following news that he is joining the board of eGym, a sports technology company, whose activities span gym and training equipment, cloud-based software and corporate health subscriptions, enabling gym users to better track their progress, evaluate their performance and personalise their training programmes.

Sir George said he had joined the business because he felt it enjoyed unique prospects.

Recalling when he ran Brunswick Corporation - whose businesses include Life Fitness, the world's biggest gym equipment maker - he said that the company spent $8,500 per employee on healthcare cover, but that this had fallen to $5,000 where the employee was a regular gym user.

He added: "So you can see in places where people have exercise as a regular part of their life, the ability to reduce costs and improve wellness, quality of life, is very, very powerful."